Elon Musk has taken on a task perhaps more challenging than launching rockets into space: getting passengers from Chicago's O'Hare airport to the Loop in 12 minutes, roughly three to four times as fast as the current taxi journey.

The plan for the "Chicago Express Loop," announced early Thursday, June 14, by Chicago Mayor Rahm Emanuel and Musk's tunneling firm, calls for the construction of an underground tunnel with concrete tracks on which "skates" - individual vehicles built on a modified Tesla X chassis - would carry 8 to 16 passengers at between 125 to 150 mph from one of the world's busiest airports underneath some of the country's most congested roads. O'Hare is roughly 17 miles from the heart of the city.

Musk's firm, The Boring Co., won a four-company competition to build and operate the underground loop. The skates, according to a fact-sheet from the company, would likely run every 30 seconds, 20 hours per day, the company said. The skates would be battery-powered and "autonomous," of course, meaning no driver.

The project will be entirely privately financed, Musk's company said. The operating firm will keep the revenue collected from passengers and any revenue from concessions. The fare would be about $25, less than the average $45 taxi trip but more than Chicago's current Blue Line route from O'Hare. No opening day for the Chicago Express Loop was offered. It should also be noted that historically, big transportation projects almost never finish on time or on budget and sometimes are never completed at all.

Indeed, the shell of the station to be used for Musk's loop already exists, deep below the spot known as Block 37 between State and Dearborn streets and Randolph. It's been sitting empty and unused for more than a decade - known as part of the "subway to nowhere"- a testament to dreams of rapid journeys to O'Hare the city couldn't ultimately afford, for which it is still paying.

But in interviews with Chicago newspapers, Emanuel expressed great faith in the ability of Musk, father of the Tesla and SpaceX, to deliver at a cost of roughly $1 billion or less.

"We're taking a bet on a guy who doesn't like to fail - and his resources," he told the Chicago Tribune. "There are a bunch of Teslas on the road. He put SpaceX together. He's proven something. The risk - with no financial risk - is I'm betting on a guy who has proven in space, auto and now a tunnel, that he can innovate and create something of the future," he said. "Given his track record, we are taking his reputation and saying, 'This is a guy in two other transportation modes who has not failed.' That's what we're doing."

"We're talking about a Tesla-in-a-tunnel," Chicago Deputy Mayor Robert Rivkin told the Chicago Sun-Times. As for the risk of an unproven technology, Rivkin told the paper that the "only real risk to the city is that it doesn't get built. . . . It's not much of a risk to have a partially-built, essentially cave-in-proof sealed tunnel 30-to-60 feet underground in some portion of the city."

"Getting from downtown to O'Hare or O'Hare to downtown is a race against time," Emanuel told the paper. "We're gonna give people a leg up."

The Boring Co. also has big plans for the Washington area. Maryland's Department of Transportation gave conditional approval to the construction of a tunnel from Baltimore to Washington for a super-high-speed transportation system, The Washington Post reported in October.

A news conference is scheduled for later Thursday to discuss the plans.

Story by Fred Barbash. Barbash, the editor of Morning Mix, is a former National editor and London bureau chief for The Washington Post. He has also been an editor at Politico and Reuters, and was the managing editor of CQ Weekly magazine.